text:
RAIM Checks when using GNSS in lieu of DME for distance information
I understand that a RAIM has to be checked on the ground as part of preflight, as well as before the commencement of an RNAV/RNP approach.
What I am unable to find information on online, is whether a RAIM Prediction check has to be done on any other non precision approaches if we are using the GNSS in lieu of DME for distance information?

If the flight is under IFR plan and you are using non WAAS equipment aircraft, GPS RAIM availability must be checked.
AIM 5-1-16 states that…
“During the pre−flight planning phase RAIM prediction must be performed if TSO−C129() equipment is
used to solely satisfy the RNAV and RNP requirement. GPS RAIM availability must be confirmed for the
intended route of flight (route and time) using current GPS satellite information”


text:
Cross crediting experience: Holder of ATC Instructor’s Qualification to NPPL(A) (SSEA)
I formerly held an ATC Instructor’s Qualification valid for the Vigilant Motor Glider through the RAF Volunteer Gliding Squadron System. I was a B1 Instructor until 2014 with 440 hours.
I would now like to obtain a UK civilian license for microlights, which I understand is still an NPPL(A) (SSEA), so I'm trying to understand what, if any, training dispensation I can use.
CAP804 (April 2015) section 2.1.6.2 states:

The holder of the ATC Instructor’s Qualification valid for the Vigilant Motor Glider who
wishes to obtain an NPPL(A) with SSEA Class Rating shall:

a) produce log book evidence of having satisfactorily completed flying training on
single-engine piston aeroplanes under the supervision of a FI(A), which must include:

i) not less than 1 hour dual instruction in stall/spin awareness and
avoidance;
ii) not less than 1 hour dual instrument appreciation;
iii) not less than 1 hour supervised solo flight; iv) not less than
4 hours navigation training or successful completion of the ‘Air
Cadet Vigilant Transit Qualification’ training syllabus, including
at least one solo  cross-country navigation exercise;

b) pass the Part-FCL PPL(A) theoretical examinations;
c) hold a valid NPPL Medical Declaration or Part-MED Class 1, 2 or LAPL medical
certificate;
d) pass the NPPL(A) NST and GST in an SSEA

However, CAP804 is now marked as "Reference Only" and I cannot find a document which has superceded it. At the advice of my instructor I have written to the BMAA for their advice, but received no response.
Can anyone tell me what the official requirements are today, please, or does it remain undefined since Brexit?

The British Microlight Association kindly wrote back to me, I don't think I'm betraying any confidentiality in sharing their response here:

On Wed, 14 Jun 2023 at 13:24, Pilot Licensing
pilot.licensing@bmaa.org wrote: Hello Daniel,
I’m afraid you are confused. You cannot fly a Microlight on a SSEA
class rating, you would require a NPPL with Microlight (M) class
rating.
Have a read of section 4 of the attached and apply your
qualifications. Cap 804 has not been superseded so remains the
document we apply credit from.
Kind regards,
Aaron Bliss BMAA Pilot Licensing, Instruction and Examinations

I've since checked and yes, to fly the Ikarus C42 I should aim for NPPL(M) not NPPL(SSEA).
The document he had attached was CAP 804 Part II (May 2012), referring to section four "CROSS-CREDITING LICENCES AND RATINGS TO NPPL (MICROLIGHT)" subsection 4.1.6:

ATC Instructor’s Qualification to NPPL(A) (Microlight) The holder of
the ATC Instructor’s qualification wishing to obtain an NPPL(A) with
Microlight Class Rating shall: a) produce log book evidence of having
satisfactorily completed not less than 15 hours  conversion training
on Microlight aircraft under the supervision of a Microlight FI,
which must include: i) not less than 6 hours supervised solo flight;
ii) not less than 5 hours navigation training, to include not less
than 3 hours solo  navigation including one qualifying cross-country
flight as defined in the NPPL(A)  (Microlight) syllabus; b) pass the
Microlight theoretical knowledge examinations; c) pass the Microlight
Aeroplanes Type (Part 2) oral examination conducted by a  Microlight
flight examiner. The examination shall include pilot maintenance
requirements and conditions of the Permit to Fly; d) hold a valid NPPL
Medical Declaration or Part-MED Class 1, 2 or LAPL medical
certificate; e) pass the NPPL(A) GST on a Microlight

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


text:
Adding a CFI-Airplane rating to existing CFI-Helicopter Certificate
Have a student who has CFI-Helicopter, and looking to get CFI-Airplane. Student has his commercial single engine airplane and wants to get CFI Airplane. What endorsements and any other factors will she need? I am aware of what will be on the checkride, by looking in the CFI-A transition table in PTS.

The post speaks of one particular student, saying "... has his {rating}" but then "what... will she need?"  If you want to obscure your student's identify, "has their CSEL" and "what will they need" is fine, but otherwise please write consistently about the individual.

You will have to meet all the requirements of §61.183 in order for said student to be eligible to take the practical test for CFI-Airplane, single engine.  The chief difference for you, and for this student is going to be they will not be required to take the fundamentals of instruction exam again, as they already hold a CFI certificate with a rotorcraft helicopter category and class rating.  They will be required to take an abbreviated version of the CFI knowledge exam specific to the aircraft category sought (see the FAA’s knowledge exam matrix). The transition table listed in the CFI-PTS should cover the pertinent areas of the practical test which the examiner will focus their emphasis on.

I think my comment addressed that.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
how to determine the optimum FL for A320 to make a flight plan?
I want to make an ifr flight plan for A320 based on fcom, but I don't understand how to make one

Generally, for longer trips it pays to climb higher.

The process of determining the optimal cruise flight level can be quite complicated. Multiple factors play into which FL is possible and practical. They include: Airspace restrictions, weather (wind, clouds, turbulence), terrain and aircraft limitations, among others.
Which altitude is optimal also depends on different factors and ultimately is the solution to an optimization problem for a mathematical function describing the relationship between aircraft range and velocity, altitude and aerodynamic factors. To finally arrive at the optimal cruising altitude, one needs to strike a balance between all these different factors.
If you want to get a flight plan with a good cruising altitude for flight simulator purposes, I would recommend using online resources like SimBrief.


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Do fuel tanks need to be pressurized?
Do fuel tanks need to be pressurized? It's my understanding that the pressure difference between the outside air and the inside fuel would force the kerosene out of the fuel tank. What stops this from happening? And if fuel tanks do need to be reinforced to accommodate for this, how do planes with wet wings, like the B-52, handle the pressure difference?

Fuel tanks don't need to be pressurized, though they can be. Unpressurized tanks are vented to the atmosphere, and so a large pressure difference never develops in the first place.
In pressurized fuel tanks, the tank is not open to the atmosphere, so fuel has nowhere to escape to. If the tank is kept at a significant pressure difference to the outside air, it of course needs to be reinforced.
The B-52's wet wings are vented to the outside air. If the vents are plugged bad things can happen.

Do fuel tanks need to be pressurized?

In some cases they need to: off the top of my head I'd say for example the XB-70.
Due to the design top speed of Mach 3, the airframe could reach temperatures as high as 250°C (500°F). In order "to reduce the likelihood of autoignition, nitrogen was injected into the JP-6 during refueling, and the "fuel pressurization and inerting system" vaporized a 700 pounds (320 kg) supply of liquid nitrogen to fill the fuel tank vent space and maintain tank pressure" (source Wikipedia)


text:
How do water bombers pick up water?
I saw a couple of CL-415s near my lake house a few days ago, and it got me wondering, how do they pick up water? What method do they use to get water into the water tanks? How long does it take to fill up the water tanks? And do the tanks get filled up fully?

Not strictly on-topic, but there is a very interesting video showing the whole process and the skills required to perform the maneuver with an Air Tractor AT-802 Fire Boss.

They scoop it up! Making contact with the water, a probe/scoop is extended, which allows water to gush into the internal tanks:

Image source: "Bombardier 415 Probe" by Wikimedia Commons user Aliano43 under CC BY-SA 4.0
The method is therefore simply a combination of aircraft forward speed and an adequately shaped metal duct. Here is another close-up good picture of the scoop, and a video showing the process from a good angle.
As for the duration, one source mentions that

“The water tanks can be filled in 12 seconds by the scoops.”

(which is what a large number of videos of this process seem to confirm).

12 seconds is 550 metres or a third of a land mile at 90 knots.  That's not including lineup and departure lines so triple it and you need a lake that is 2 km long and wide enough.

@Criggie according to this https://aerialfirefighter.vikingair.com/firefighting/firefighting-technique the specs are: 6.5 feet deep, 300 feet wide, and a total distance of 1,340 meters, but a diagram below the table implies that the water surface may be shorter than that - likely if there are no trees/hills/obstructions around the water source. The minimum water surface for a full load would be 410 meters, in that context (I think they’re using slightly slower speeds than mentioned above)

It also says “If the designated water site doesn’t have the capacity for a full water load, a partial load will be used and the CL-415EAF aircraft will make multiple trips, returning to the fire.” which would imply to me that they can do partial loads if there’s not a sufficiently long water source

It's interesting to compare that with railway practice https://en.wikipedia.org/wiki/Water_trough where again the scoop depth was of the order of a couple of inches and the trough length around 500 metres with a bit less than 2,000 L picked up per run.

For a quick calculation, the hydraulic head goes by H=v²/g. At 90kts=45m/s² this is over 100m of hydraulic head, or about 10 bar. No wonder it fills up fast.

As stated above, either the flying boat superstructure, or the pontoon floats on the aircraft are fitted with “scoops” - ram intakes just fed of the step, which direct water up into a holding tank, mounted inside the aircraft. The aircraft makes an approach onto a lake or river with the scoops deployed, then maintains a high speed step taxi over about 10 to 20 seconds. The ram pressure of water hitting the scoops forces it up into the holding tank. Once filled, the aircraft will take off again and retract the scoops prior to heading out for another drop.  Alternatively, the water tanks can be filled from trucks on the ground, or filled up with a mixture of water and chemical retardant prior to take off.
The TV series Ice Pilots: NWT featured a good segment in the episode below starting at time index @30:55, where Buffalo’s chief pilot Arnie trains Turkish Air Force pilots on how to scoop water and makes water drops in a CL-215.

When scooping up water in a high-speed step taxi, care must be taken to maintain a constant attitude with the appropriate increase in power to compensate for the quick increase in weight due to filling the water tanks. If you get it wrong, you can start causing the water to slosh around in the tanks, resulting in a pilot induced oscillations, and potential risk of an accident.
For both of CL215/415 and the Air Tractor Fire Boss, the scooping operation typically takes place in the neighborhood of 85 to 90 knots, depending on the air frame.


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Is there a good way to search for all special livery flight or widebody aircrafts from an airport
As a planespotter, I want to search for a list of widebody or special livery flights that depart an airport on a certain date. Is there a quick way for me to search for such stuff?

I found a couple of tools like airgeek.link and JetTip


text:
Do seaplanes need to say their intentions before landing on uncontrolled water?
Do seaplanes need to say their intentions before landing on uncontrolled water? I know you don't need to say your intentions to take off in uncotrolled water but what about landing on one?

Only if the water is within a Mandatory Frequency zone established around an uncontrolled airport with adjacent water landing areas. An MF is a CATF that must be used to broadcast intentions IF you have a radio.
MFs are common in Commonwealth countries but rare in the US (Ketchikan AL apparently has mandatory use of its CATF). With a MF, if you have a radio, you are required to use it. If NORDO, well, you don't and NORDO airplanes are free to come and go from uncontrolled airports.
Otherwise, as with an uncontrolled land airport, you are not legally required to broadcast your intentions in any situation with a water aerodrome in uncontrolled airspace, and don't even need a radio. You just use common sense and do what others are doing at a particular landing area if there is other traffic and a common radio frequency being used.
Coming and going from remote lakes when I was bush flying, in the middle of nowhere, I never broadcast intentions when there was nobody else around, only if a lake had other airplanes coming and going.

Hey John, do you have any videos on YouTube of your bush flights? Would love to see

No sorry, my bush flying sojourn was in 1990.

then you could write a book about your career, it would undoubtedly be a fascinating read

Too short to fill a book. A magazine article maybe.


text:
General Thin Airfoil Theory
I can't understand where the equation in the blue circle comes from or is derived from, I know it says the sum of the perpendecular components should be zero, but can you explain visually? and what exactly does the B angle, the flow angle, represent?
$$-u\sin B+v\sin B=0$$

It's written just before the equation: "The velocity component perpendicular to the airfoil profile is zero". What's not clear? The equation itself? Or why it is zero?

The equation itself is not clear, I mean where did this equation come from?

Ah ok, that equation just translates the fact that the speed perpendicular to the surface must be zero since the airfoil is "airtight" i.e. no air can flow though the wing. $\beta$ is simply the slope of the airfoil so that $u sin \beta$ and $v cos \beta$ are the speed components perpendicular to the airfoil and their sum must be zero. Mathematically this is called "boundary condition".

thank you for your comment, can you explain visually if possible

You have to look at the velocity decomposition at location $y_u$.
Below I made a velocity diagram at location $y_u$:

If you decompose $u$ and $v$ into the red velocity (tangential to the surface) and the blue velocity (perpendicular to the surface), which formulae do you get?
Then the text goes on to say that the velocity perpendicular to the airfoil surface is 0, so what happens when we apply that knowledge to our just-derived equations?

Thank you for your attention and answer. It made me feel deprived of math :d. My mistake was to assume the y-axis is "perpendicular"

That equation just translates the fact that the speed perpendicular to the surface must be zero since the airfoil is "airtight" i.e. no air can flow though the wing. This condition is normally termed "non-penetration".
$\beta$ is simply the slope of the airfoil and equals, by definition, $dy_u/dx$ and $dy_l/dx$.
Being $u sin \beta$ and $v cos \beta$ the speed components perpendicular to the airfoil, the non-penetration condition simply gives that their sum must be zero. Mathematically this is called "boundary condition".


text:
How can I calculate the surface area of a plane wing
I want to determine the surface area of an aircraft wing using calculus, specifically focusing on the cross-sectional area (thickness distribution) formula. Although I am unsure if there exists a specific formula for this purpose, I am interested in understanding how to calculate the curved surface area of an airplane wing without relying on aerodynamic equations. I have provided images, which may aid in visualizing the three-dimensional aspects. In the figures, the cross-sectional area is defined using airfoil equations, incorporating a thickness distribution equation. (I asked this question on Math Stack Exchange but didn't get an answer so I decided to ask it here.) Second image
It is noteworthy that the cross-sectional area of aircraft wings tends to increase as they approach the fuselage, with C1 and C2 representing the initial and final chord lengths. The variable L denotes the length of the aircraft wing.
General Thickness Distribution formula:
$$y_{t}=\pm5ct[0.2969\sqrt{α}-0.1260α-0.3516α^{2}+0.2843α^{3}-0.1015α^{4}]$$
Thickness Distribution formula for NACA 2412 (which I want to find): $$y_{t}=\pm0.60[0.2969\sqrt{α}-0.1260α-0.3516α^{2}+0.2843α^{3}-0.1015α^{4}]$$
Where c is the chord length, α = x/c and t is the maximum thickness expressed as a fraction of the chord length. In other words, 1/100 last two digits×chord length.
It is not necessary to use the given values, but you can if you want.
$$L = 30m$$
$$C1= 3m$$
$$C2= 1.5m$$


text:
Diesel engines market share in Piston Airplanes market
I am just trying to understand the diesel engines market-share in the piston airplanes market.
Any experience or idea about that ? Just to understand if it is 1% or 10% or more.
Thanks in advance for whom will reply to me.
JT77

This answer will help for sure.

It's about 5%, very approximately, but might be approaching 10% in the EU.
https://www.experimentalaircraft.info/homebuilt-aircraft/aircraft-diesel-manufacturers.php - overall list
https://www.continental.aero/diesel/diesel-engines.aspx - Continental advertises 7500 diesels installed, and they're the main player.
There's 200k GA aircraft in the US, about 130k are single piston engine, or 140k total piston. That's the largest market by far. So the numbers come out to 5 and up to 10% of piston-powered GA aircraft being powered by diesels.
No particular reason. Nothing wrong with them. They work great. Range is much better, fuel's half the cost per mile, weight increase is similar to fuel weight decrease, noise is bad for both diesel and avgas.
It's just that so many GA airplanes have already been built with avgas engines. And new planes are expensive just for being new. Retrofits cost money, one needs a solid reason to do it, just saving on fuel isn't always enough.

Why are new avgas planes still quite common?

@Someone Inertia, maybe image of car diesels as "cheap and noisy" (in aviation, low air density makes forced induction much more useful), slightly better hp/lbs ratio on the ground for avgas engines. Maybe other things. New engines run fine on mogas, though, they don't need the expensive and poisonous leaded version, and injection narrows the gap somewhat. Diesels still win on efficiency by a good margin.

Thank you so much Therac for the information! Really appreciated.


text:
Airbus A320 Business class seats power
I have acquired a pair of old business class seats taken from an Airbus A320.
They have old 4:3 individual screens and power reclining and massage chairs. Wonder if anyone could guide me to powering them up with some schemes and power needs/specs to make them running.
As for the moment I’ve been using them with manual reclining (each seat has 2 knobs that release the hidraulics for the back reclining and foot rest) but would like to fully use them with electrical reclining.
Thank you

Where did you acquire the seats? Whoever sold or gave them to you might have a wiring diagram or something else that could help?

Can you find a manufacturer or supplier name / number on the seats?  Most transport aircraft interior components are supplied by subcontractors -- different airlines will customize the interior just the way they want.  The seats are not likely to be made by Airbus.

@RobMcDonald, Agreed, Zodiac is possibly the provider, acquired by Safran.

You'd need documentation or to open it up and do some basic reverse engineering of the motors - be aware there is a reasonable probability that the motors are 400hz, which will run badly or even catch fire connected to 50/60hz domestic power so do the homework before 'just plugging them in'

I would speculate that the seats do not include the computer required to make the screen work the way it did on the airplane.  Also, I am nearly certain the seats do not include hydraulics.


text:
why you have to open 6 bypass valves in the J 58 engine?
I've noticed that the bypass valves in J-58 are opened after M=1.6. I don't understand why and what are the differences between the J-58 and a normal turbojet that reeaches more than M=1.6.

At that point, the rearmost fan discs in the compressor stage were near their temperature limits (remember, the first stage/inlet compressor fan disc was managing air at 800 F). The bypass ducts limited the temperature rise in the final compressor stages. By that point the compression work performed by the inlet duct system and the remaining stages of the compressor were sufficient to run the afterburner.

Not only that, but compressing the air further would had heated it so much that combustion would had become inefficient.At these temperatures, chemical energy would go into molecular dissociation instead of further heating.


text:
How can I optimize galley space utilization?
I am working on a project aimed at improving the galley (inserts) of a commercial aircraft. My focus is on "" I have discovered that the galley often takes on a U-shape design, and the corners tend to be underutilized due to limited accessibility. Some aircraft have trash compactors placed in the corners, but this significantly adds to the aircraft's weight, making it an unsustainable solution. Additionally, there is often insufficient space for waste storage in the aircraft, as waste is typically disposed of in bags, which consumes a significant amount of space. Ideally, waste should be efficiently and quickly sorted to minimize space usage and facilitate recycling. And at the same time it would be nice to also compact the waste.
I am seeking information on practical construction plans and dimensions for the galley, highlighting unused spaces. Additionally, any knowledge on the weight of aircraft trash compactor components would be valuable. Any other tips, insights or ideas related to optimizing galley space utilization are also welcome.

Where did you try to find the answers yourself? It seems there is some literature on galley design already, perhaps you could consult those.

Wide open "how might I design this thing better" questions aren't a good fit here.

As usual, optimisation is always a compromise between different factors. While trash volume might be a problem, separating the trash also takes up both space (for sorting and later storing in different containers) and valuable time for the crew.

Note: on airplane the weight is more important then space (e.g. for a compactor), also separate waste takes time (on short/medium haul we do not have it; on long haul there is also rest period). Corner spaces: sinks (so you do not need to access water collector), and electrical cabinet can be placed). Check youbute videos of cabin crew to get an idea on what they need (and the little trick that they use: which may be solved in a better way). Space optimization is probably not so important.


text:
What would happen if both engines of a twinjet cut out at or immediately after V1?
Disclaimer: Not a pilot or an aviation guy, just someone who's flown on planes before.
So, yeah. Assume A and B are the PIC and copilot, respectively, of a twin-jet plane (doesn't matter which one). B calls out "V1" and half a second later before V2/rotation speed both engines "magically" cut out. So, now what would A do? Or what would you do? Conventional wisdom says you should only reject the takeoff over V1 is the aircraft is incapable of flight, and I would point out that having both engines fail before you can even take off, with less than enough space to decelerate safely, is the epitome of an aircraft being incapable of flight.
Would this be a situation where there isn't really more to do but cross your fingers, and slam on the brakes, figuratively speaking, and hope that you stop before you overrun the runway or stop short enough that everyone survives? The thing is gonna stop at some point thanks to physics. Might as well ensure it stops as safely as it can, then assuming everyone's alive or not too badly unhurt, have a chat with the NTSB/local regulation authority about it.

With no engines running, you ARE NOT going to go fly, and the only choice is how hard you work to slow down, so that you go off the end of the runway slowly, because you worked hard, or fast, because you didn't initiate any braking.  I'd recommend closing this question since it's really a duplicate of your other one, and I've addressed that scenario in the answer there.

@RTO That was my other question, yes.

You really answered your own question here in the body of remarks...  What else is there to say?

Basically, yes. You will get on the brakes and hope for the best. If the runway is 10000 ft and your accelerate stop distance at max thrust is 7000, no problem.
If the runway is marginal, or you are using a "flex thrust" power setting (where you use just enough power to meet the departure requirements of that runway, to go easy on the engines - flex is widely used), you are cutting it close, but there is some fudge factor built into the distances, where for example, it's assumed there is a couple of seconds delay in getting on the brakes. You might roll of the end, but you won't be going very fast, and if what's off the end is inhospitable, like approach lights or a cliff, you might decide to drive off the side of the runway instead when getting close.
Actually, the "go no matter what" concept post V1 isn't completely cast in stone. A captain may elect to reject after V1 but before rotation, where something happens that casts doubt in the ability of the airplane to fly, such as a loud bang coming from the back just after V1, and there is excess runway margin available. A rare circumstance, but possible.
As a statistical matter, the double simultaneous engine failure is not even accounted for in risk analysis, because the probability is well beyond the risk threshold at which you must mitigate the risk of a complete loss of the airframe by design; namely, a probability worse than 10⁻⁹, or one in a billion.

Yeah -- the more realistic case of rejecting after V1 is because your plane simply refuses to fly (such as if a tab-flown elevator is jammed and won't let you rotate, to bring up a couple recent examples)


text:
What is this Luftwaffe branded plane at Tirana's airport?
The question is pretty much in the title, I was definitely not expecting to see a Luftwaffe branded plane, so I'm curious to know what I'm looking at! At the time of posting the plane is sitting at Tirana's international airport

https://en.wikipedia.org/wiki/Executive_Transport_Wing_(German_Air_Force)#Current_Fleet (I was expecting an executive aircraft, but instead is usually not used for government transportation). Wild guess: UN forces, or maybe a change of crew on an army ship in a nearby port.

The aircraft 15+11 is an Airbus A321LR (the long range variant of the A321neo) operated by the German Air Force (Luftwaffe) as a troop transporter and MedEvac plane:

The Air Force has taken delivery of the second Airbus A321LR from Lufthansa Technik in Hamburg. The aircraft with the tactical identification 15+11 will soon be available to the emergency services for troop transport and parliamentary flight operations - and will be given another task in 2023.
The 15+10 is followed by the 15+11: Germany has two state-of-the-art A321LRs for special Air Force tasks. Starting next year, both aircraft will also be equipped for medical transport and evacuation flights (MedEvac).

(aero.de News, 2022-08-19, in German, translated by Google)
It arrived in Tirana yesterday evening from Frankfurt:

(flightaware.com)
The flight was probably for the German Foreign Minister and her delegation who arrived in Tirana yesterday to discuss the recent tensions between Kosovo and Serbia (thanks to @DeltaLima for the link).

From this article, I infer that the German minister of foreign affairs is visiting Tirana . It's very likely she was on that Lufwaffe aircraft.

@DeltaLima Yeah, that's probably the reason. She is usually using one of the executive jets (white livery), but then again the German Air Force isn't exactly known for their reliability, so maybe this was the only one available xD


text:
How to calculate the Traffic Advisory (TA) range limit above the maximum altitude limit (take 16000 ft) of an aircraft?
Let us consider an aircraft(A) with 16000 ft maximum altitude limit. Above which it cannot achieve 0.25 G vertical acceleration with 1500 FPM. Now, my question is if there is an aircraft(B) flying in an altitude like 16200 ft above our aircraft(A), does the TA advisory will be generated or not. What will be the TA range limit of our aircraft(A) to consider the aircraft(B) as a TA advisory threat above the maximum altitude limit. How to calculate the TA range limit?

Please consider which uses of "TA" in your post should be revised to the acronym of a different advisory.  The dynamics you're talking about may be used in TCAS, but not with respect to TA's.

Yes I'm talking about the TA and RA advisories given by TCAS II System of an aircraft.

Consider the difference between what a TA tells the crew, and what an RA tells the crew. Performance plays no role in presenting a TA. In fact, a TA is generated even without an altitude for the target. Having altitude on the target might suppress the TA if vertical separation is great enough, but that's it.

It does not factor in. Why would it? The lower aircraft does not know the higher aircraft's intentions, and an aircraft passing 200 feet above is definitely a threat. The higher aircraft does not know the lower aircraft's performance numbers.
Two aircraft within 200 feet of each other are a collision risk if their horizontal paths are converging, and a traffic advisory and then a resolution advisory will be issued as the convergence becomes imminent.


text:
How to calculate the amount of differential cable delay between a four port directional antenna and a single port Omni directional antenna in TCAS II?
I want to select the amount of differential cable delay between the top (4-port directional) antenna and the bottom (1-port Omni-directional) antenna in the TCAS II RBP-7G connector pin.
In the ACSS TCAS II installation manual, there are four options can be selected in the RBP-7G pin, which is only one-time configurable during the installation. They had given 0-51 nsecs, 51-120 nsecs, 120-200 nsecs, 200-350 nsecs.
I know how to calculate differential cable delay between two cables, which is done by subtracting the cable delays of the two cables. But my question is how to calculate differential cable delay between a 4-port (4 cables) top directional antenna and a single port (one cable) Omni directional antenna.
Is it right to calculate the difference between each of the directional port to the Omni directional port (or) we can just sum all the delays of the directional ports and then subtract the total delay of the directional antenna with the Omni directional antenna delay.

While this is installed on an aircraft, seems like it would be a better question for [electronics.se].

Cable delay is identical on each of the 4 cables connected to the Directional antenna. In the ACSS system, the 4 cables are the same length and the delays ARE NOT additive. (Please forgive me for shouting!!)
For the calculation you are trying to make, take any one of the 4 upper cables, calculate for that single cable against the bottom Omni cable, and the job is done.
Good question.

That makes sense


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Cessna 182 Climb Performance
I have this in the POH for a 182P I'm renting. I am failing to understand the lower table on the performance page. It says that for a gross weight of 2,950 at sea level and 59F, I can expect a climb rate of 890 ft/min. That's fine. But then, it says 1.5g of fuel used - for what? Per minute? Or? And then at 5,000 ft I can expect 3.8g of fuel burn from sea level - again - from sea level to what altitude? 5,000 ft?
I'm sorry if this is obvious to everyone but me
Thanks in advance!

This is a classic case where we have to read the notes associated with the performance chart very carefully and understand what is going on.  Note 2 states: “Fuel used includes warm up and take off allowance” ie from the time you start up your engine on the ramp to the time you are climbing away from the airport, you will burn approx 1.5 gal of fuel. To reach 5000 ft @ stp and MTOW, you will burn another 2.3 gal during the climb giving a total fuel usage at this point of 3.8 gal.

Thanks so much for your reply and help!


text:
Height from the ground of aircrafts doors
I'm searching for the height from the ground of these AA/CC doors (front and back)

Boeing 737-800
Boeing 737-8200 (800-max)
Airbus A319
Airbus A320
Airbus A321
Airbus A220
Airbus A340

I know only these approximate heights (in meters)
A/C              FRONT  BACK
----------------------------
Boeing 737-800          ~2.9
Boeing 737-8200
Airbus A319
Airbus A320       ~3.4  ~3.4
Airbus A321
Airbus A220
Airbus A340

Is there a website with these specifications?

Yes, the airframers' airport planning guides will have this information.
Airbus
Boeing/McDonnell Douglas
Former Bombardier A220 CRJ and Dash 8
Embraer
Door heights are usually specified as a range because, like a car, the landing gear compress as the aircraft is loaded and the center of gravity shifts.

Although it wasn't part of the question, a harder number  to obtain for some aircraft is the height from the doors to the bottom of the fuselage. This is a number which can come into play if landing with the gear up. Even more useful would be the height of the doors above the ground in various gear retracted/broken off situations, like nose gear retracted/missing, etc.

@StevePemberton It's not really relevant because you buy the firefighters ladders to reach the doors in normal conditions. If the gear collapses, then the height is decreased, so your ladders will satisfy that condition. Nonetheless, the charts list the height between the ground and the nacelles, and the ground and the fuselage, so just subtract the two. Rear doors are usually unusable in a nose gear collapse anyway (slides may not reach the ground), but the gear and door distances are all in the docs for a calculation.

user71659 - In a fire situation they can't always wait for firefighters with ladders. Jumping from a front door with a failed slide would likely cause injuries on most airliners, but if the plane is resting on its nose the front doors might be viable. Subtracting nacelle height only tells you the fuselage height above the ground if resting on the nacelles with the plane level, it doesn't give you the door distances from the ground. The rear doors are obviously not viable with a collapsed nose gear, but maybe in some cases they are with collapsed main only

This is a link only answer -- a prior such link only answer was deleted.

@StevePemberton That's why you subtract the fuselage-ground clearance height, or specific points like the belly fairing-ground clearance on the A320, which is slightly lower. That data is all in the documents.

user71659 - Yes I can see now that Airbus provides fuselage height above the ground, so by subtracting from door height above ground you can calculate door height above the fuselage. But Boeing doesn't seem to provide fuselage height above the ground. And it still wouldn't tell us what the expected door height above the ground is with various collapsed gear. These documents are for airports, maybe Flight Attendant training documents get into what my question is about. As I mentioned this info is harder to obtain, probably something not for public consumption.


text:
what is the cross section of an elevator and trailing edge flap?
Is the cross section of both a Trailing edge flap and elevator an aerofoil please or, like i've shwon in in image below? I tried to find a side view of an elevator and TE deflected to see this for myself, but couldnt find one

I can't help but notice that in the past few days you asked several questions about basic aeronautical and aerodynamics concepts. I'd suggest you to read a good book about those concepts instead: getting a lot of answers from random guys on the internet is definitely not the best way to learn this kind of subject. "Aircraft performance and design" by Anderson is a classic.

Hi Sophit, thanks for the book. I swear I did do research into this question, but just haven’t been able to find anything.

What do you think this image represents if it is NOT an airfoil with deflected trailing edge?  I'm just not understanding your confusion here.  If you have done enough research to locate an image like what you posted, it would seem that you would understand what it represents from the context where it first appeared.

I generated that image in cad Michael- I just wanted to know whether the cross section of an elevator and flap is an Aerofoil or like I’ve done

What you have done is an airfoil, with a hinged trailing edge.  (roughly...)  Is that what you were trying to create?

Many elevators have airfoil shapes.
The precise way you've drawn the flap is not physically possible.  It is drawn as a shear of the trailing edge.  That would involve deforming materials.
Instead, a control surface has a hinge and there is a rigid body rotation about a single axis.  This usually means that the front of a control surface is an arc about the rotation axis.

On small general aviation aircraft, it is not uncommon for the elevator to be made out of welded metal tubing and covered with fabric.  In this case, the elevator (and its control surface) will be flat plates with circular leading and trailing edges.

In general, to prevent control surface flutter, control surfaces need to be balanced (mass) around their hinge.  In addition, it is often beneficial to add some sort of aerodynamic balance in front of the hinge.  This is an extension to the surface that reduces the force required to deflect the surface.

Hi Rob, can I ask for the book you got those nice pictures from please?

No book, just a random website.  I did a google search for control surface hinge or something like that.


text:
What is meant by "shroud" in a gas turbine? For example, an inner shroud and an outer shroud in a vane device in a gas turbine? Thank You
Vane device comprises inner shroud, outer shroud, aerofoils. I cannot understand what shrouds are, and their function.

Do you have a reference where this phrase is used? I’ve heard of a screech liner, but that’s something totally different.

Sorry, this phrase is used in  a patent which I don't want to quote in greater detail, due to confidentiality reasons. It is exactly as i reported it. Thank you anyway

Generally speaking the shroud in a turbine engine is a flat plate located at the end of the blades which helps to keep the gases from "leaking" past the tips of the blades for better flow, and also to minimize vibration. A more detailed description can be found on the WENZEL America website.
In this photo of an interior blade of an RB199 turbofan engine the shroud is on the right.

RB199 blade (author: Stahlkocher, via Wikimedia Commons, CC-BY-SA-3.0)
Even though in most cases there is an individual shroud for each blade which butt up against each other, the entire structure is often referred to in the singular as a shroud. This diagram shows how it looks when the individual blade-tip shrouds fit together.

Turbine shroud (author: unknown, this diagram appears unattributed on multiple websites)

Turbofan engines essentially use the wall of the engine inlet as a shroud for the fan blades, as seen in this photo:

GE90 (author: Dysanovic, via Wikimedia Commons, CC-BY-2.0)
Although there was a question here about why the fan blades of turbofan engines don't have individual shrouds, and one of the answers included a photo of one that does, the F108 (CFM-56) engines that are used on the reengined KC-135 tankers.

F108 turbofan engine (Tinker Air Force Base)
I have seen the blade tip type of shroud referred to as an "outer shroud". I couldn't find anything explaining what an inner shroud is.

Very clear and exhaustive explanation. As regards the "inner shroud" the phase I submitted relates to stationary vanes, not to rotor blades. I think that it is something like a vane supporting ring, formed by indvidual foot platforms or "shrouds" of the blades. At least, this is what I understand. In any case,thank you very much

Luciano Grazzini - while for jet engines the term vane is normally used to refer to the stator (stationary) vanes,  in discussions about gas turbines in general it also seems to  often be used to refer to both stationary vanes and rotating vanes, aka blades. So as you do your research make sure that it's clear which type of vane is being referred to as you look at various sources. If you find an answer regarding stator vane shrouds you can post it here as an answer, it is allowed to answer your own question in Stack Exchange.

EP 1956196, among others, "is directed to a vane shroud of a gas turbine engine §[0004]. In same source, it is stated, e.g., §[0001] that "compressors and turbines are comprised of alternating stages of stator vanes and rotor blades..." and in Claim 1 "A vane shroud of a gas turbine engine..." So, may I infer that the phrase "vane shroud" can refer to a shroud (an individual or common annular component) associated to one or more (stator) vanes in gas turbine of jet engines, as well as for stationary use (power plant)? I understand that this terminology is commonly used in patent literature.

Luciano Grazzini - seems like the term can have multiple meanings. Omniseal sells what seems to be a fixed ring shroud around the fan blades. In this Rolls Royce patent it seems to mention a wall and a skin shroud used for cooling. Another Rolls Royce patent is an inner shroud for a stator vane. A Raytheon patent is for an inner shroud for a variable vane system.


text:
What is the specification of control cap (control tower) glass in FAA?
Does anyone know where I can find the specification of glass for control tower?

UFGS 08 88 58 - AIR TRAFFIC CONTROL TOWER CAB GLASS

This guide specification covers the
requirements for engineered outward sloping low-iron
clear annealed tower cab glass for use in military
air traffic control towers.

Also see §151 in FAA Order 6480.7 - AIRPORT TRAFFIC CONTROL TOWER AND
TERMINAL RADAR APPROACH CONTROL FACILITY DESIGN GUIDELINES.

WINDOW GLASS


text:
why stabilator has a lower travel limit for down movements?
Within the POH of my aircraft, in a part titled "Control Surfaces Travel Limits", the manufacturer states:
Stabilator:        Up 18°  ---  Down 3°
Why stabilator has a lower travel limit for down movements?

Maybe because you'll never have to do a landing flare upside-down?

what is the aircraft model?

Most aircraft can handle higher positive G loading than negative, which allows more "up" stabilator than down.
Also, most aircraft center of gravity limits are such that the stabilator has positive trim (for static stability).
The third reason is it is usually not a good idea to steer aggressively towards terrain.  The aircraft natural longitudinal stability (tail feathers) will help pitch down if airspeed slows to a point where insufficient lift is created.

+1 for the phrase "steer aggressively towards terrain".

Not only can aircraft handle more +g's than -g's, the same is true for humans.  Fighter pilots who can take +9g's with a g-suit, training, physique, and technique will red out at -2 to -3g's.

Stabilator angle determines angle-of-attack of the main wing, since it trims the balance of forces in pitch to set the wing AOA that the static stability forces of the "system" (the wing and tailplane opposing moment interaction) will seek.
The low AOA trim point (high speed) will be with the stabilator chord line somewhere closer to parallel with the main wing chord line, that is, minimal decalage. The high AOA trim point (low speed) will be with a significant decalage (to generate the maximum trimming down force to hold the nose up).
So you have a range of motion of the stabilator surface, 21ᵒ in this case. Leading edge all the way up is maximum speed, all the way down is minimum speed.  Some point in that range needs to be set as a datum for rigging purposes.
The datum is normally the airplane's horizontal axis or close to it (typically the upper fuselage longeron), and this will be referenced as zero degrees for rigging purposes. The actual range of movement above and below this is determined by the aerodynamic requirements.
In your particular case, with the stabilator set parallel to the longitudinal axis, designated as "zero degrees" as a rigging reference, the range of motion for maneuvering and trim is leading edge 18ᵒ below that datum for minimum speed, and 3ᵒ above that datum for maximum speed.
So basically, you have that odd asymmetrical up-down range, because the neutral point datum is offset to one side because that's where the rigging neutral is set for convenience.

The purpose of these design limits is to prevent the pilot from inadvertently overcontrolling and overstressing the aircraft during normal maneuvers.
The quote is from a FAA document

The limits are designed in the process of getting the type certificate. Type certificates referr to different categories. A plane in the Acrobatic category will have different (larger G-forces) limits as compared to a Normal category plane.
My guess is that the manufacturer has designed the plane for low negative G forces but higher positive, and hence the difference in control authority in the pitch axis. Always remember that the design process has to make compromises, say between strenght of aircraft parts vs weight or cost of the parts.


text:
Over which types of ground surfaces do we have more updraught?
When a light airplane is flying around 2000-3000 ft AGL, over which places will it deal with updraught more?

If you're talking about thermals from the sun heating the ground, it depends on the surface's solar absorption/release characteristics, and this has a lot to do with moisture content, variations in the surface composition and the air mass's stability.
The vast majority of the sun's energy that reaches earth's surface is absorbed into the air by conduction and transported up by convection, or, absorbed into water vapour via evaporation. This means that where water is present, it tends to slow the release of energy by conduction.
The result is you get strong thermal updrafts from dry surfaces that tend to absorb and release energy quickly. Large asphalt and concrete surfaces, rocky areas, dry fields with minimal foliage.  Wetter surfraces, lakes, wet fields, swampy land, wherever there is higher moisture, tend to produce weaker thermals that start and stop later in the day, due to the heat sink and storage effect of the moisture.
The other big variable is the stability of the air itself, a function of its lapse rate (temperature change with pressure). Unstable air has a higher lapse rate is more easily encouraged to start rising when energy is added.
This is all why the worst days for unpleasant bumpiness are sunny, dry weather days over dry terrain (deserts are the worst); good for glider pilots (if the wind isn't too strong), bad for power pilots wanting a smooth ride.
I prefer to fly my power plane outside of the strongest solar heating periods because of this (for soaring, the opposite). Early morning or later afternoon if the sun is out, or during overcast weather.
If the winds are strong, mechanical turbulence from air flowing over contours like ridges becomes a factor, even on overcast days where thermal activity is minimal. So at those altitudes expect a rougher ride over hilly terrain for a few thousand feet above the surface, depending on how hilly it is and how strong the wind is, even if it's overcast or too early in the day for thermals.
If you're taking someone for a ride in a power plane in sunny weather, try to arrange it for morning before 9 or 10 am, or in the early evening, say after 5 pm. With light winds as well to minimize mechanical turbulence.


text:
What is the behaviour of attitude indicator with a lower than standard gyro speed?
How does attitude indicator behave if its gyro is spinning at lower revolutions per minute than its designed specification?

I did a little bit of research on this.
A gyro spinning slower than normal will cause the attitude indicator to be sluggish to respond and slowly fall out of position. Worn-out bearings on the gyro mean it won't be able to spin as fast as it should to maintain the required RPMs to display a true attitude. The indicator's slow falling out or sluggish movement is known as precessing. The readings will slowly drift out of place.
sources - https://www.mcico.com/resource-center/articles/attitude-indicator-error-erecting-mechanism#:~:text=Worn%20out%20bearings%20on%20the,there%20is%20too%20much%20friction.

But, there is a mechanism to compensate for precession, so-- if you were flying straight and level, would it really fall out of position?

how much can it compensate... there will come a point where it'll fall out

Please share the research itself, linking to an authoritative source that supports your conclusion. As it stands, your answer amounts to "somebody on the internet claims that..." without any real support, and for somebody disinclined toward the presented conclusion, that's not really a credible answer.

@RalphJ  thanks for the advice, will follow in the future, have edited my answer.


text:
What is the difference between QNH and QFF?
I am wondering what is the difference between QFF and QNH?

See also this answer (ignore the math equation in the question; the text of the answer is far easier to follow than the text of the question).

Both QNH and QFF are pressure measurements at a meteorological station (e.g. airport), with the pressure height-corrected back to sea level.
The difference is in the assumptions that are used for the correction to sea level reading. QNH assumes standard atmosphere (for temperature, lapse rate and humidity) and QFF assumes actual atmospheric measurements for the correction.
Since a barometric altimeter uses standard atmosphere assumptions, with a pressure correction, the result is that when you put QNH is the Kollsman windows, the altimeter will read measurement station elevation at the measurement station (e.g. the airport). In a non-standard atmosphere, the altimeter will now deviate from 0ft at sea level.
If you put QFF in the Kollsman window, the altimeter will read 0ft at sea level. However now the altimeter will deviate from the airport elevation at the airport.
Since we typically want the altimeter to be correct at the airport, QNH is the normal setting.


text:
How diesel fuel is injected into the cylinder of a diesel engine?
I am wondering how is diesel fuel injected into the cylinder of a diesel engine. Despite the difficulties of detonation, I think maybe a gradual injection of fuel during the power stroke will be helpful. Is it correct?

Diesel Fuel Injection, there is a method called split injection.

How, please, is that about Aviation, unless you're suggesting Diesel engines work differently in aviation than they do for instance on roads, railways or ships?

maybe a gradual injection of fuel during the power stroke will be helpful

That is correct. Modern diesel engines inject fuel gradually. The main purpose of this is to ensure a slower burn of the fuel charge rather than a single, large combustion event. This lowers the peak pressures and temperatures in the cylinder.
Lowering peak pressure reduces engine noise and vibration. It also allows higher average combustion pressure for a given engine, allowing more power from the same package. Lowering peak temperature reduces the formation of NOx.
Older engines using unit-injection technology (1990's) were able to do a split-shot, that is a single early injection leading up to the main injection. Modern common-rail diesels (2000's+) can have multiple injection events.
These are classified as early pilot injections, in the compression stroke, to warm the air for a gradual burn. The main injection delivers the fuel for power for the main combustion event. Because the air charge has been warmed, combustion begins earlier, while the fuel is still being injected, smoothing the peaks. Then post-injections serve to reduce the pressure drop-off rate (noise, vibration), and help burn off particulate matter formed in the main combustion event.
Finally, systems may use an after-injection, injecting fuel during the exhaust stroke in order to introduce unburned fuel in the exhaust stream. This fuel is combusted in downstream catalytic converters to both help them light off (initial warm-up) faster, and to be used in particulate filter regeneration.
The ability of common rail diesel injectors to have multiple, electronically-controlled injection events is central to the efficiency, smoothness and emissions performance of modern diesel engines.

The fuel is injected at the top of the compression stroke, timed as you would time the firing of a spark plug. The fuel starts to burn as soon as it atomizes in the combustion chamber due to the temperature of the compressed air. Detonation isn't an issue because the burn is controlled directly by the injection of the fuel itself. The torque level of a diesel is so high because the burn can be initiated and sustained in way that maximizes the pressures at the optimal range of the power stroke.
This requires very high pressure fuel pumps, operating at thousands of psi, which is why when the pump goes bad in a diesel car or truck, the replacement pump's price will make your eyes water.  Cars with gasoline direct injection are similar, but with lower pressures and with the ignition initiation still controlled by a spark.
Diesel aircraft engines for general aviation have only become feasible in the last couple of decades as the metallurgy has advanced enough to make a cylinder that can take the intense amount of multi-stage supercharging boost (they typically use both mechanical and turbo supercharging together, like some WW2 aircraft engines), required to get a power-to-weight ratio that can compete with a gasoline engine.

Last para graph - There were diesel aero engines in WW2 - Jumo started with them in the early 1930's, and they were used in high altitude recon planes that could fly higher than a petrol/gasoline powered fighter, albeit slower.  Curiously they were also 2-stroke diesels.

I believe the 2 stroke was done to get the necessary power to weight. They were still pretty heavy tho.


text:
Can cellular towers be used to correct INS drift?
At a high enough altitude a line-of-sight can be established with multiple cellular towers. Can such information be used to accurately correct INS drift (assuming GNSS is not available)?

Most commercial aircraft FMS's are capable of using radio nav from VOR towers along with INS position to obtain accurate position information. Very simply, it's a lot like GPS only instead of satellites the aircraft is pinging radio towers with a known fixed location.

No, for several reasons:

There is no receiver onboard (granted, this could be remedied easily)
Cells are very small, their antennas are directional privileging ground. Detection from an aircraft is difficult. For an aircraft in cruise, the distance is at least 10 km, only a large cells found in rural areas would be received. In populated area cell radius is much smaller.
Aircraft switch from a cell to the other, most of the time before being able to create a stable link. This may be a problem or not, depending on the distance measurement principle. If the principle is based on measuring radio trip time rather than azimuth, a synchronization with the cell controller is required.
On the other hand, if angles are used to determine distance, triangulation is not really accurate as the angles are small, less than 60° by design. In addition receiving antennas must be phased arrays (or rotating antennas) to determine the transmitter azimuth and elevation.

Last but not least, this would interfere with the cell network working. This reason is among the critical ones cell phones must be powered off while flying on a fast aircraft like an airliner. Cell phones on US aircraft are not prohibited by FAA but by FCC (its scope of interest is frequency protection, not aircraft safety). When a cellular network is available in flight, then there is a tiny cell in the cabin,connected by satellite link to the ground telephone network. Same for WiFi. There is no connection with a ground cellular network.

what about drones?

drones are: slow so no frequent switching, fly low so not a small angle

If you mean determining the drone position from cells, yes it would be possible, but maybe not allowed in some countries.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
How likely is it that there is someone knowledgeable about piloting in a flight control room?
I saw a reasonably looking video about a non-pilot trying to land a plane with the help of a flight control tower (in a simulator):

 (it is in French).
I believe that this was an ideal case where the plane was compatible with the airport so that the landing was almost automatic (they showed a short version of (successfully) trying to land without the automatic mode).
The person in the control tower was extremely knowledgeable about the plane, explaining exactly where to press, where to look etc.
Assuming that the whole exercise was realistic - how likely is it that there would be someone handy who could, by heart, explain via the radio what the exact steps to take are?
Note: I realize that the situation will be different between a large airport (where they could make an announcement "we are looking for a Boeing 747 pilot, please contact the reception desk if you are one") and smaller ones. In the video, they started from a cruising altitude and it took minutes to go from "there is nobody in the cockpit" to "listen to me carefully, I will guide you". It is more the realism of time which I am trying to assess.

Similar video by Captain Joe: Can a passenger land a plane?.

@PerlDuck: it is an interesting one! The conclusions are also different (not realistically possible for a passenger to land a plane)

And yet the lady in Captain Joe's video managed it. Btw, almost all of CJ's videos are very interesting. I learned a lot from them about how things work or what they are good for.

As your example was in France, then FYI, ATCO (ICNA) curriculum in France includes obtaining a PPL and learning IFR basics, at least when training at ENAC which trains also for ATPL. It's not uncommon to see CPL pilots and even instructors in control rooms in this country.

If by Flight Control Room you mean Air Traffic Control, not very likely. Simulators are operated by flight instructors. They will role play ATC for the “pilot” being instructed. So of course, they know the aircraft intimately.
There is no requirement for ATC personnel to even have a pilot certificate. If they do have a pilot certificate, they will not be type rated in that particular aircraft. They may be able to help with a GA aircraft.
For a commercial aircraft, they will reach out to a non-ATC pilot of one of the airlines whether that pilot is in the airport terminal, pilot lounge, or even in the air. More likely, they will patch the cockpit into the maintenance and training departments of the particular airline that owns the plane in danger.

The answer depends a lot on the type of plane being flow.  While plenty of air traffic controllers are also pilots on the side, it is highly unlikely that anyone on duty at the time would happen to have a type rating in a large complex turbine aircraft, and/or enough knowledge to talk through checklists.  They may be able to offer very generic advice such as "See the handle that is shaped like a wheel?  Push it down and that will lower the landing gear."
For simpler GA aircraft they might offer some basic assistance on how to control the aircraft, slow down, deploy flaps, etc. but there is a lot of muscle memory and technique honed by hours of practice needed to perform a "good" landing.  Just explaining the exact steps to take over the radio isn't going to be enough, there is a lot more to it.
Think about the first time you drove a car with a manual transmission:  Did the person telling you to push in the clutch, shift gears, then let it out smoothly while adding gas help you to do it smoothly, without stalling the engine, jerking, or racing the engine?  Probably not!
About the best they could probably hope for is to help the non-pilot maneuver into a safe airspeed envelope to survive a controlled crash landing at the airfield where emergency services will be on hand to provide immediate help.

Not only that... but typically control towers are located at airports, and airports are one of the easiest places to find pilots. It isn't unreasonable that they could find a pilot to head up to the control tower and talk.

Yeah, but I think it would be more than "just a few minutes" before they got someone on the radios with experience in that exact model...

In this case, the passenger landed a two-seater with the help of flying instructors based at the airport.
During this incident, ATC phoned a type-rated pilot and relayed instructions.  The passenger did have 150 hours on spamcans but hadn't flown for years and never a turboprop
When her husband collapsed, the wife of a pilot was talked down by another pilot in a similar aircraft while they were both in the air.  Again, she didn't have a licence but she had solo-ed


text:
How much can a plane deviate from its route to Paris (CDG and ORY) before an alert is raised?
I was reading about the 9/11 hijacks and the Wikipedia information about flight AA 11 mentions that

Of the four hijacked aircraft on 9/11, the nine minutes of advance
  notification about the hijacking of Flight 11 was the most time that
  NORAD had to respond before the aircraft crashed into its target.

I am sure that these tragic attacks have lowered the bar in terms of time to react to a off-route deviation by planes and was wondering what this means for flights to the Paris airports CDG and ORY.
I have just taken a snapshot of the flights (courtesy of flightradar24)

and it seems like (quite understandably) that planes avoid Paris intra muros. This said, they are quite close and the ~20 km distance from Paris is a ~2 min flight.
Since the closest airports which may host Rafales are I believe Le Bourget and Vélizy-Villacoublay, the interception planes would need much more than that to be on their tracks before they entre Paris.
With all this said, how much can a plane deviate from its path before Paris before it is intercepted (and brought down a way or another)?
Note: while I am particularly interested by Paris (living there) I can understand that the information is classified (though probably easily guessable for someone who knows about aviation). In that case another public information is welcome to understand how things changed after 9/11.

This is probably impossible to answer. If, for instance, a rogue pilot wanted to crash into the terminal building they’d have only seconds

I think "it seems like (quite understandably) that planes avoid Paris intra muros" is jumping a bit to conclusions. I went to Flightradar24 and found this, without even waiting for anything interesting to happen:

It didn't go exactly over the Notre-Dame, but even on this scale you should be able to see that it did cross inside Boulevard Périphérique.
On the other side of the Channel, such overflights are extremely routine when Heathrow operates east-to-west (as it usually does). Here's one (again found live, without waiting for it) that could have dropped bombs on the Crown Jewels if it had any to drop:

Perhaps more relevant than the Crown Jewels, this flight path is just a few hundred meters from the City of London skyscrapers. If the pilots had wanted to reenact 9/11, they could have crashed into something tall and famous about 10 to 20 seconds after deviating from their expected horizontal flight path. (But they'd need a bit more time than that to descend -- call it a minute or so from the first non-routine control input).


text:
How does the passenger load impact the direct costs and pricing strategy?
I am sitting at the airport and I was wondering if there is an optimal number of passengers to try to board a plane through an interesting fare.
Flying an empty plane is obviously the worst situation: you have fixed costs and fuel costs that depend on the weight of the plane. For an empty plane your gain is 0% (all loss, 100% would mean breaking even and anything above that is pure gain).
As you start to add passengers, their weight is added (say, 110 kg per passenger and their luggage), which means more fuel to buy. But you also get some income so you are raising up from 0%.
Is the relationship gain(number_of_passengers_boarded) such that the weight passengers add is insignificant, semi-significant, or a key factor? Is the curve always raising (which means the more passengers - the better, until all space is exhausted)? This will certainly depend on the plane, so with two reasonable extremes (a typical regional jet vs a long-haul jet) are there key differences?
In other words: is it always interesting to lower the fare as the start date approaches? (purely from a gain perspective, I am not taking into account ways to optimize this for a passenger by, say, waiting until the last moment)

Fill the plane up with payload, that's what they're designed for! The industry has high fixed costs, plus the variable costs per flight to carry the plane without payload to its destination. The revenue is from payload per flight only - so what is needed is maximising flights/year, and maximising payload/flight, to make revenue.

The slide above is from this presentation, and lists the various cost categories - costs per year, per flight, per kilometre,per route, per seat. Revenue is per seat-kilometre. Fuel necessary for the trip is determined shortly before departure, while selling seats takes much longer before departure. All these variables create a multi-dimensional matrix for determining profitability, making the consideration of extra fuel burn per passenger kilo almost meaningless. Yes a 1% saving in weight results in a 1% fuel saving, as per this answer, but sell the seats! and control all costs!

If the cost of the ticket is less than the cost of the fuel necessary to carry the added weight of the passenger, his baggage and the extra fuel required to carry them, then no, it is not beneficial to fill another seat at any cost.
Additionally, cargo capacity not taken by passing passengers (self-loading-cargo) is often used to carry non-self-loading-cargo, so the capacity doesn't always go to waste. Cargo can be more profitable than passengers, so there can be limited pressure to fill the seats by lowering the price.


text:
Why does QR1173 take such an indirect route?
QR1173 from RUH to DOH takes a very indirect route (at least to my untrained eye):

What is the reason for that? A direct route would be entirely on KSA and Qatar territory where there are no particular risks (as in avoiding a war zone).

It's definitely not a Mercator map distortion.
It could be the threat created by Houthi militia launching missiles and drones from Yemen, targeting Israel. Over the last years there has been strikes in the south of Jeddah FIR (OEJD). From Conflict Zone & Risk Database:

Missiles should fly on the western part of KSA, however there are also navy ships of several countries intercepting these weapons from the south part of the Red Sea, these interceptions could lead to objects falling in southern KSA. In addition Houtis have also targeted airports in KSA prior to the Gaza strip conflict.
This FIR has active warnings (more here) for the south:

The primary risk is from Houthi drone and missile attacks on Israel, shipping in the Red Zea, and prior attempts on airports across the country, but particularly in the south.

but also in other areas:

Nov 2024: Red Sea Conflict Zone risk. Saudi lies between Yemen and Israel, and there have been in excess of 220 missiles and drones fired across Saudi Arabia in the last 12 months. A missile intercept incident near Jeddah on Nov 3 (observed at close proximity by transiting air crew) has highlighted the risk to civil aviation, and has made it clear that this area is an extension of the Israeli conflict.

From FAA Saudi Arabia/Yemen: Houthi UAS Attack in Riyadh:

On 10 March 2022, Yemen-based Houthi forces launched an attack against an Aramco oil refinery in Riyadh, Saudi Arabia, utilizing multiple unmanned aircraft systems (UAS), which caused a small fire. No major damage or casualties were reported. The most recent prior long range attack into Saudi Arabia occurred on 3 January 2022 near Taif.

KSA issued the Emergency Security Control of Air traffic (ESCAT) procedures in April 2022, they are still active. Several routes are described. I haven't drawn the routes on a map, but I guess the one described in your question is part of the selection.

Thank you. The location of Riyadh (and its east area) is not really anywhere in the conflict area but your explanation makes a lot of sense. Better worry then sorry, I guess. Thanks again.


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How big a risk is to abort take-off before V1 with uncontained engine fire and side-wind?
The Blue Panorama flight 1504 had uncontained engine fire just before V1 during take-off. The pilot continued the take-off and succesfully landed the plane with one engine. In the TEDx talk the pilot Maurizio Guzzetti explained that he thought that if he had followed the official protocol he would have aborted the take-off and the heavy sidewind would have pushed the heat from engine fire to the cabin and caused the cabin to catch fire and result in casualties. Instead he decided to take the plane to air, turn the plane around and land with the other side to the wind before stopping the plane. Note that the plane was over the maximum landing weight and no ability to dump fuel.
Do you think that this was a real threat and if so, what should a pilot do with similar fire starting with slower speed? Assuming the fire cannot be contained and heavy side-wind is there a reason no believe the cabin will not burn, too? However, if you're a lot before V1, it really wouldn't make sense to try to complete take-off with only one engine.
The TEDx talk: Collaborating with machines at high altitude and speed | Maurizio Guzzetti | TEDxModenaSalon

A well made animation about the accident:
Bursting into Flames Just Before Takeoff in Rome | Season Finale [Real Audio]


text:
How far can a 777 fly with just one engine at altitude?
If a 777 pilot wanted to fly further than with both engines running, how many more miles could the plane go with just one engine running, at high altitude?

I really like the proposed edits. While the OP 'really' wants to know about the lost airliner, questions like this are seemingly 'fishing for conspiracy theories.'

While the answer on this question is correct that it wouldn't go farther, I'd be interested to hear the actual answer to the title question. That is, if it lost an engine and the flight crew didn't have to care about ETOPS limitations, how far could it fly? I'm assuming the answer is "a really long way," but I'm curious approximately what that distance is.

On one-engine, a multi-engine plane can always make it to the crash site.   (or so the joke goes).

@abelenky -- the joke only goes for CAR 3/FAR 23 aircraft -- a FAR 25 bird like the triple-seven can do V1 cuts all day without ever leaving the pilot wondering if they'll make it.

How high of an altitude are we thinking here?

Flying with only one of two engines will not increase range, but reduce it. A gas turbine consumes fuel in proportion to the mass of air moving through it, so with increasing altitude consumption decreases proportional with air density. Thrust goes down with density as well, so thrust-specific fuel consumption is roughly constant (actually, the engine becomes more efficient with altitude due to the lower air temperature, see Carnot cycle for more on that).
Generally, a jet transport wants to fly as high as possible for maximum range. Its cruise altitude is limited mainly by the thrust available from all engines. If the pilot shuts one down, the aircraft needs to fly much lower until thrust has increased sufficiently to overcome drag. Since friction drag is also proportional to air density (and the square of flight speed), the aircraft has to fly much slower at that lower altitude, which cuts range since the fuel consumption of the single engine is now roughly what both consumed at altitude, but now the aircraft covers less distance in the same time. In addition, the pilot has to compensate asymmetric thrust with rudder deflection, which again increases drag.
Short answer: The aircraft will not go MORE miles, but FEWER.

Excellent answer thank you. So, I assume it is NOT possible to use both engines (777), get to cruise altitude and then shut one engine down and NOT lose altitude using just the one engine? The drag as you explain of the non running engine and deflection of the control parts does make sense. I was just thinking IF the running engine was powerful enough to not drop the airspeed or altitude, seems at altitude, a jet plane could go further? (Or does the math just not work that way with aerodynamics for any amount of single engine thrust?)

In any case, cutting one engine will also cut thrust in half, and will slow the plane down. If an airliner has thrust reserves, it will (ATC permitting) climb higher to cruise more efficiently. The engines run close to maximum thrust during cruise, so there is no reserve to compensate for the switched-off engine. If there were, the designers would have made a grave mistake.

What I am trying to get at... how far could that lost 777 go if someone REALLY wanted to "shake things up"? It someone REALLY thought things out. IF everything in the passenger area was thrown out and lightened up the plane say 50,000 pounds, would it make a 1000 mile difference? Something is really off on the missing 777. If that experienced pilot got really board with live and was a bit "off", maybe he thought of things that most people would never consider? The plane has yet to be found... There are too many odd things on that flight that indicate anything other than "normal" happened.

For that case, please see the answer for http://aviation.stackexchange.com/questions/3367/how-do-airliners-get-from-the-factory-to-the-client-if-the-aircraft-does-not-hav

@user2667 It's impossible to open the cabin doors of a 777 in flight (due to the pressure differential,) so there's no way to throw stuff out from the cabin in flight.

@PeterKämpf What percentage of engine power do they actually use at cruise? I was under the impression that close to full power was only used during TO/GA. And just from personal observation, I know the engines are at least much louder on a 777 when it's climbing than when it's cruising (even if it's just climbing a couple of thousand feet to increase cruise altitude after burning some of the weight off.)

@reirab: Your observation is correct, however, the thrust settings are very close to full thrust when measured as percent of maximum shaft RPM. Engine wear goes up proportionally with T4, the turbine entry temperature. If the ambient air temperature is -50°C, which is typical for 35.000 ft, T4 will be comparably low with 96% of RPM, which is typical for cruise.

@PeterKämpf When you say 'RPM' do you mean N1, N2, both, or something else?

@reirab: The primary display usually shows N1, but my 96% figure would be for N2, because the wear happens in the HP turbine. N1 in cruise is typically 85% to 92%, depending on altitude, temperature and aircraft mass.

@PeterKämpf Interesting. So, then the (rather large) increase in engine noise during climb is the result of just an additional ~4-5% N2? I haven't measured the difference, but just from casual observation when sitting aft of the engine, I'd say the difference is around 20 dB.

@reirab: At full power the engines are really noticeably louder, but my impression is that this is due to vibrations and resonance, and not necessarily coming from the engine's core.

Just as a practical example of reduced range with an engine out, We departed Santiago, Chile in a 747 freighter with enough fuel to reach Miami. During the climb out we lost an engine. We elected to continue rather than dump fuel and return. However, because we could not reach our intended cruising altitude, the increased fuel burn meant we only had enough fuel to reach Panama City, Panama.

@Terry: And that was with only 1/4 of your thrust gone - imagine what it would be like in a twinjet.

Oddly enough, around holding speed at medium altitudes, shutting an engine down on some twins increases range, as the remaining engine runs at much higher efficiency to provide the thrust required. Total range in that regime, though, is much lower than at higher speeds and altitudes with both engines.

It depends on the airliner design.  If one engine is inside the fuselage tail section and can close side intake scoops and streamline engine bypass cowling, then range will increase as drag is a lot lower with one engine out of the air steam, and the remaining outside engine will have a higher engine rpm, hence higher efficiency using less fuel for the needed thrust. Chances are the needed thrust will be available as engines spool down quite a lot at cruise (oversized to take off). However, the higher thrust will decrease the life of the single cruise engine. Of course, the single cruise engine could be sized to take advantage of this condition to maximize fuel efficiency at normal wear.

This seems to address the possibility of designing an aircraft to cruise on fewer engines, but the question is about a regular 2-engine aircraft cruising on one engine.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


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Why the number 6 in P6SM in a METAR/TAF?
A typical METAR or TAF reads something like this:
VRB04KT P6SM SCT025 BKN040 OVC060
P6SM means "greater than 6 statute miles visibility."  Why in particular is it 6 miles--why not P7SM or P10SM?  Particularly since sometimes METARs and TAFs list actual visibilities greater than 6 statute miles anyway:
28006KT 10SM CLR
Is 6 miles a limitation of commonly used equipment for measuring visibility, or something else?

The METAR format is defined by the World Meteorological Organization's (WMO)  on behalf of ICAO. According to the specification (section 15.6.3), visibility is to be reported in meters. The upper bound for visibility reporting is 9999, which indicates the visibility exceeds 10 kilometers.
In North America, the METARs deviate from the standard format by using non-standard units. Visibility is reported in statue miles. Six statue miles is equivalent to 10 kilometers.
Hence > 6 statue miles is equal to the standard > 10 kilometers.

Note that automated systems use P10SM, but reports generated by an official weather observer sometimes report more, such as 20SM or 50SM, so I believe that it is a limit of the measuring systems in use.  The AWOS wiki also states that it can measure up to 10 SM.

@Lnafziger that's because ICAO uses 4 digits of meters (not km) and USA uses 4 digits of statute miles (not feet), so the US can report up to 9998sm, and ICAO can report upto 9998m.

My comment was meant to address that sometimes you will see METAR reports with something greater than 10 miles, but not from automated systems.  He asked if it was an equipment limitation, and based on that I'm guessing that it is.

@Lnafziger There are automatic reporting systems that exceed 6SM: KBLH 061852Z AUTO 00000KT 10SM CLR 16/M04 A3029 RMK AO2 SLP256 T01611044

You are correct!  ASOS & AWOS actually report up to 10SM.  It is the TAF which is limited to 6SM.  I will updated my original comment and delete the extras.

The reason its reported as "greater than 6 statue miles" is because 6 statute miles is the equivalent of 10 kilometers. ICAO reports METAR visibility in meters, and reserves 4 places in the coded METAR for the number of meters.  With only 4 places, 9999 is the largest value, and this corresponds to "10km or more."
Reference: Aerodrome forecast - TAF  decode

P6SM - "P" = Plus 6 Statute Miles...in conversational writing we are more used to seeing the plus sign "after" the number, as in 6+, but that's what P6 means. Usually anything less than 7 miles requires an explanation why the "VSBY" (visibility) is less than 7, so there will be an obstruction of some kind included, such as 3SM BR (BR is French, "Brume", mist).

authors: Константин Ван


text:
What, if any, would be the most correct term for the aerodynamic flight control surfaces of SpaceX's Starship?
SpaceX's Starship uses a unique flight control scheme during descent that I have not seen anywhere except with skydivers: it falls straight down belly-first using four aerodynamic control surfaces at the nose and the bottom to induce drag and thus provide pitch, roll, and yaw control, somewhat like a skydiver uses their four limbs.
 [Time lapse by @asy on Twitter, original source footage by LabPadre.]
This is a pre-flight actuation test of the aerodynamic control surfaces. The Starship is in its launch attitude, i.e. tail-down / engines down. On descent, it would be falling belly-down, where the belly is the side facing away from the camera, i.e. if the vehicle were falling right now, we would be looking at it from the top.
These aerodynamic control surfaces have been called lots of names by the spaceflight community: fins, flaps, wings, flings, wing-dings, flippety-flappety-bits (yes, really). Tim Dodd, the Everyday Astronaut, sometimes jokingly calls them Elonerons. SpaceX themselves only name them once on the Starship website, where they use the term flaps. Elon Musk uses both flaps and body flaps in tweets.
They are, however, different from many of the concepts mentioned above, in that they act perpendicular to the airflow. The closest analogy I can think of, other than a skydiver's limbs, is how the Northrop Grumman B-2 Spirit uses differential speed brakes for yaw control instead of a rudder.
Given that we have so many names for so many different types of control surfaces (e.g. flap, slat, spoiler, aileron, elevator, rudder, speed brake, horizontal and vertical stabilizer) as well as combinations of them (spoileron, flaperon, stabilator (all-moving tail), "ruddervator" (V-tail)), etc., there must be some term we can apply to these?
What I am looking for is a term that concisely conveys what these control surfaces do, in much the same way as everybody knows what an "aileron" or an "elevator" does. Or, alternatively, an answer could be that such a term does not exist.

I like "attitude control variable drag brakes".

As far as I know, the only other example of this flight profile in aviation is post-stall maneuvering, especially for flat spin recovery. For planes, control in these flight regimes is mainly accomplished by thrust vectoring and canard/stabilator actuation. The Starship flaps don’t match these.
Another close sibling of this flight profile is the Shuttle reentry. The Shuttle used a body flap as well as conventional Delta-wing control surfaces in combination with RCS to maintain a specific, high AoA during hypersonic reentry, then transitioned to gliding for approach and landing. The Shuttle body flap (under the engines) has the closest resemblance to the Starship flaps out of any space vehicle I know. It has a much smaller actuation range, though.
Of course, the control surface naming depends on how you define the vehicle frame; with thrust direction-forward, the flaps are variable-dihedral. With velocity direction-forward, the flaps are variable-AoA with a wide actuation range.
The noun I would go with would be variable-drag flaps. Spoilers aren’t correct; there isn’t another airfoil to spoil. Airbrakes usually don’t contribute to attitude control.

The Space Shuttle body flap also came to my mind. The hypersonic entry profile is indeed very similar between Space Shuttle and Starship, using the "broad" side of the vehicle to maximize drag, but of course what happens after most of the velocity is bled off, is the major difference. (Although I believe SpaceX did test cross range capability using the body and flaps for lift during the SN8 test flight. They are "gliding" the F9 after all.) The Shuttle would keep a horizontal velocity component and glide, whereas the Starship cancels the horizontal component completely and falls straight down.

Elonerons is perfect, although birds beat him to it years ago.
Birds "tuck" a wing to slip/fall to one side while the opposite wing is extended. They can also vary the geometry of their tails (opening and closing the fan) for pitch control.
Elon's 4 finned craft simply does the tuck for pitch and roll, or combinations of both.
The Starship in "belly flop" bore a striking resemblance to an incoming shuttle, and it is not hard to imagine later iterations with a central wing.  This would not be unlike the "jib, main, and jigger" rigs of sailboats.
But, for now, it "flops" its way home, using drag.  Hopefully, next landing approach may be stabilized enough for a softer touchdown.  Go SN9!

Stability wasn't the problem -- Elon has tweeted that it was lack of pressure in the header tanks, causing loss of thrust at literally the last second.

@Zeiss Ikon The SN8 prototype will be basal to many possible iterations.  An earthly point to point design may have wings, and indeed a recoverable 1st (rocket) stage.  This design would closely resemble the Nike Hercules.  I have my doubts the "flop/flip" will be comfortable for passengers, but it is a start.

The belly flop is actually likely to be more comfortable than other vertical landing options -- G forces are either through the floor, through the seat backs (assuming nose-facing seats as in an airliner), or somewhere in between.  No hanging from the straps.  And the high drag configuration allows gradual deceleration, high up, so no high G slow-down in the lower atmosphere.

"Gradual deceleration from higher up": Earth = wings, Mars = large parachute, Moon = bigger header tanks

Doesn't have to be wings.  Any large, low density object will decelerate from air drag, and the more cross section area for its mass, the higher (=thinner air) this can effectively be managed.  Wings are a mass penalty, carrying heavy structure that's only used for a tiny fraction of the flight.  If you can land without them, you can save that mass -- and every ounce of dry mass you can save is an ounce more payload you can carry with the same engines and fuel.

Looking forward to the next flight.


text:
Amount of fuel consumed
Airliners have 200 tons of fuel. Assume less than 10 hr flights.
An airplane flying all day consumes 4,200 barrels in 3 flights. Us jet fuel consumption is 1.5 million barrels per day.
Is it impossible to fly more than 400 airliners at any time?

How does fuel consumption factor into your question?  Do you think that somehow consumption is the limiting factor vs actual number of available airplanes?  If so please help us understand your confusion so somebody here can give you a better answer.

It seems so I understand.

There's one 0 too much in your barrels count: in 3 flights it's more 420 barrels than 4200. USA counts for more or less ⅓ of the worldwide consumption of jet fuel.

I guess you are a troll and you're going to be blocked, sorry because the question was actually interesting...

@sophit this person is an uber-troll

Is it impossible to fly more than 400 airliners at any time?

I invite you to count the dots.
From flightradar24, just now.

No, it is not impossible to fly more than 400 airliners at any time.
According to Spikeaerospace.com:

Every day, some 93,000 flights take off from approximately 9,000 airports. At any given time, there are between 8,000 and 13,000 airplanes in the air.

So in fact, a great many more than what you might consider possible actually fly every single day.

@mins, I'm just posting the first thing that came up on a quick Google search.  Still an order of magnitude over our local troll's "impossible" figure.

This figures are right. IATA statistics 2014: 100,000 commercial flights per day.

Your math is wrong. A 737, for example, burns 850 gallons per hour, which is about 20 barrels. That is only 480 barrels per day even if the plane were running 24/7. There are larger airliners that burn more, but even a huge airliner like an A380 doesn't get close to 4200 barrels in a day.